- Persons with military experience or having served as a military contractor attending the same clinic or hospital as the myositis subject to which they are matched, or if not available, volunteers from the general community (such as other participating military or VA hospitals, private HCPs, or the NIH Healthy volunteer program), gender- race- and age- (within 10 years) and military service period (within 10 years) matched to the myositis subject. Military contractors include those with at least 1 year of collective service on a military base or who actively deployed with military units after October 1998.